Digital Light & Color

Similar to the Level transformation, the Warp transformation could offer a pair of vertical bars and a pair of horizontal bars for precise alignment of perspective for vertical and horizontal subjects. Alternatively, an alignment quadrilateral could be offered for simple alignment of a rectangular surface, such as a building wall or a painting.

The endpoints could be numbered 1-8 ( or 1-4 for the quadrilateral ), for use in quick zooming, similarly to the level transformation n ( endpoints 1 and 2 ).

... In the case of an alignment quadrilateral, something similar to the composite transformation for overlays with 4 alignment points, which can be refined, would be quite useful.